Early life

Abu Hassan was born on 15 September 1940 in Bukit Belimbing, Kuala Selangor, Selangor. He received his early education at the Malay School of Bukit Belimbing (1946–1950) before furthering his studies at Klang High School (1951–1957), Malay College Kuala Kangsar (1958–1959) and University of Hull, England (1960–1963 and 1971–1973). Abu Hassan was married to Wan Nor Daud and the couple had five children.

Before entering politics, he served as Administration and Diplomatic Officer (ADO) from 1964 to 1978. He previously served as Chief Assistant Secretary of Economy Planning Unit in the Prime Minister's department, Assistant Secretary of Selangor State Government and Assistant Secretary of the Land and Federal Territory Development Ministry.

On 30 April 1997, he resigned as Member of Parliament for Kuala Selangor and his cabinet minister post in order to contest the Selangor state seat of Permatang by-election which fell vacant when its incumbent assemblyman, Jamaluddin Adnan also resigned. This arranged position swap occurred to enable him to be appointed the new Selangor Menteri Besar, to replace Muhammad Muhammad Taib who stepped down over currency irregularities court charges and controversies.

Menteri Besar of Selangor

After being elected as a representative of the Selangor State Legislative Assembly in the by-election on 29 May 1997, he was appointed as the Menteri Besar of Selangor from 6 June 1997 to 9 August 2000. There was controversy over the RM5 million expenditure to renovate the official residence of the Menteri Besar at Bukit Megawati, Shah Alam for Abu Hassan during his tenure.

In 2000, a poison pen letter started circulating about an alleged sex scandal and ill-concealed relationship between Abu Hassan with his wife's sister. Abu Hassan had denied any wrongdoing, claiming his sister-in-law actually had married his good friend, a Chinese new Muslim convert (Muallaf) who coincidentally shared his Islamic name; Abu Hassan Tan Abdullah. He stated that as the reason their son's name was Mohamad Hafiz bin Abu Hassan, which had caused all the confusion. The opposition had reported the case to the Selangor Islamic Religious Department (JAIS) demanding an investigation into their relationship and if they have an illegitimate son under religious law.

On 10 August 2000, Abu Hassan abruptly announced his resignation as Menteri Besar of Selangor citing health and family reasons but did not elaborate on other existing controversies and crisis bothering him.